Keyboard key



Oct. 28, 1952 J, GROBL 2,615,547

KEYBOARD KEY Filed 001;. 28, 1949 INVENTOR- Jon E. (12cm.

Patented Oct. 28, 1952 KEYBOARD KEY Jon E. Grobl, Oakland, Caliii, assignor to Friden Calculating Machine 00., Inc., a corporation of California Application October 28, 1949, Serial No. 124,011

7 Claims. 1

This invention relates to an improved means of pressure bonding a control key to a keyboard key stem, and more particularly to a means of preventing the relatively heavy plastic control keys of business machines and the like from becoming detached from their associated key stems during high speed operation or" the keyboard.

In the construction of automatic calculators, typewriters, and similar business machines, it is often desirable to rapidly return the key board or control keys to their inactive or full raised position. t is frequently the practice also to improve the general appearance of the machine keyboard by shaping each control key in the form of a cylindrical shroud which is adapted to conceal from view as much of each upwardly extending key stern as possible. This construction and arrangement frequently increases the mass of the individual control keys to such an extent that forces of sufficient magnitude are produced during high speed operation of the keyboard to loosen and ultimately separate the control keys from the key stems unless a highly efiicient bonding or securing means is provided to prevent such separation. It is also desirable that the effectiveness of such a securing bond between each control button and its associated key stem be substantially undiminished as a result of the reduction in the structural strength of the plastic buttons which occurs when they are exposed for prolonged periods of time to relatively high operating temperatures.

It is an important object of the present invention to provide a self-locking keeper which can be readily installed on a keyboard key stem at normal room temperatures for establishing an effective bond between the key stem and its associated plastic control button when the latter is pressure fitted thereon.

It is another object of the instant invention to provide a reusable securing means which can readily be installed on a keyboard key stem at normal room temperatures in such a manner as to establish an efiective self-locking shear engagement between each keyboard key stem and its associated slightly elastic control button after the latter has been pressure fitted thereon.

t is also an object of the present invention to establish at normal room temperatures a selflocking shear resistant connection between a keyboard key stern and an associated relatively heavy plastic control button which must be rapidly accelerated and decelerated during release from its depressed position, the said connection being effective even at elevated operating temperatures to prevent creeping upward movement of the said control button on the key stem during continued high speed operation of the keyboard.

It is still another object of this invention to provide a reusable keeper adapted to be installed on a keyboard key stem and operable to establish a highly effective self-locking engagement between the key stem and its associated plastic control button when the latter is press-fitted into a predetermined position thereon, which engagement is operable to substantially prevent progressive separation of the control button from the key stem whenever the keyboard is continually operated at high speeds and in the presence of elevated operating temperatures.

Further objects are to provide a construction of maximum simplicity, economy and ease of assembly and disassembly, also such further objects, advantages, and capabilities as will fully appear and as are inherently possessed by the device and the invention described herein.

The invention further resides in the combination, construction, and arrangement of parts illustrated in the accompanying drawings, and while there is shown therein a preferred embodiment thereof, it is to be understood that the same is illustrative oi the invention and that the invention is capable of modification and change and comprehends other details or" construction without departing from the spirit thereof or the scope of the appended claims.

Referring to the drawings:

Fig. l is a plan view of a typical keyboard key assembly utilizing the present invention.

Fig. 2 is a transverse cross-sectional View taken along the lines 22 in Fig. 1.

Fig. 3 is a longitudinal cross-sectional View taken along the lines 3-3 in Fig. 1.

Referring now more particularly to the drawings, in which like reference numerals indicate like parts in the several views, there is shown a keyboard key assembly for a calculating machine, typewriter, or the like, which assembly comprises a slightly elastic control button 20, a keyboard key stem 22, and a readily installed and reusable securing means adapted to be interposed therebetween. Control button 29 is molded or otherwise formed of a suitable thermo plastic material which is slightly elastic and has limited flow characteristics such that plastic deformation is slowly produced whenever the plastic material is subjected to pressure for prolonged periods of time and at normal room temperatures. Button 2% has an upwardly extending vertical slot or recess 24 therein whichis shaped to generally conform to the external configuration of the top portion 25 of the key stem 22 so that button 20 may be inserted therein and pressure fitted thereon. Button 20 may be of generally elliptical cross-section with flattened end portions 2| as illustrated in Fig. 1, or it may be of circular or other suitable ornamental cross-section, if desired. A plastic inlay 26 containing a contrastingly colored identifying numeral or letter is cemented, molded, or otherwise imbedded within the upper surface 27 of the control button, and provides a convenient means of visually identifying each keyboard key assembly.

Key stem 22 is punch-formed from a relatively thick sheet of ferrous or nonferrous metal, and has a rectangular, circular, Or other suitably shaped aperture 28 formed centrally therein at a convenient distance below the lowermost extremity of control button 20. Key stem 22 preferably, but not necessarily, has an ofiset shoulder. 30disposed on each side thereof between aperture 28 and the top edge 29 of the key stem,

which shoulder 39 forms a seat for the control button 20 when the latter-is installed thereon in the manner illustrated in Fig. 2. In some applications, however, the offset shoulder 3:] may not be. required, in which case the width of recess 24 in button 2!} is uniform and is substantially equal to the width of key stem 22 throughout the entire, depth thereof. In instances wherein the seat provided by the shoulder 38 is not desired, the. uppermost surface 29 of key top 25 may be pressed into seating. engagement with the coacting topsurface 32 of the interior recess 24 within the control button 23. Thus, the general configuration of the preformed interior cavity or recess 24 is substantially the same as but slightly larger than the coacting top portion 25 of key stem, 22, so that the latter willbe received in, free sliding engagement therewith when no securing means isinterposed between the to lof key' stem 22 and button 22.

A means is also provided which can be readily installed on a keyboard key stem and which is operable at normal room temperatures toestablish an effective self-locking and binding engagement between the key stem and its associated plastic control button when the latter is pres.- sure-fitted thereon. Referring now to Fig. 3, it will be apparent that the thickness of the. recess 24 formed within the plastic button 201 is approximately equal to the combined thickness of the key stem- 22- and thesheet metal clip or keeper 23 which lies longitudinally along one side thereof. Clip 23 is shaped to conform generally to the configuration ofrecess 2 i", and preferably isformed by a rectangular lower base portion 34 and an integral upwardly extending rectangular top or tongue portion 35 of reduced width connected to the lower base portionby the: shoulder. 30; The up-per'portion of keeper 23 is provided with. a flanged top 33 adapted to override thev upperedge 29: ofkey top 25.. The lower base portion 3 3 of keeper 23 hasa hook or- U-shaped ear 3? on the lower edge thereof, WhiCh.hk'.iS adapted to. be; inserted through the aperture 28 in -key: stem 22- and-tobe retained in clamping or pressing engagement with the upper edge of aperture 28. when keeper 23 is installed. on the keylstemdn the manner illustrated in Fig: 3; Extendingoutwiardly from the keeper 23, on the op- 'posite side thereof: from flange-33g and hook 31, isQa. pair. of vertically disposed. pips, nipples, or protuberances which havebeen. pressed intov the central portion of' the cli or keeper*23'.. Prefer-- riorly within the control key 20.

4 ably, but not necessarily, the upper nipple or click 38 is disposed slightly above the level of the shoulder 30, whereas the lower nipple or click 39 is vertically disposed slightly therebelow so as to provide a vertically aligned tandem locking arrangement.

In operation, hook 31 on clip or keeper 23 is inserted through aperture 28 in key stem 22 for pressing or bearing engagement with the upper surface thereof, and th top flange 33 of thereusable keeper 23 is moved into contact with the coacting top edge 29 of the key stem. The plastic control key 20 is then placed on top of key stem 22 and the. key assembly is placed in a suitable. press so that sufficient downwardly directed pressure may be exerted on the top surface 21 of the control button 20 to force keeper 23 and key top 25 into the coacting recess 25 formed inte- A the press fitting operation continues, the lower inner edge 3t of button 20 moves. progressively into contact with the respective upper and lower protuberances 38 and 39- on clip 23, and the magnitude of the downwardly directed pressure is then increased so as to deform the adjacent plastic material without shearing or tearing the same. and with the result that the button 20 is finally moved into thefully seated position on the key stem 22 illustrated in Figs. 2 and 3. Because of the. binding or force fitting engagement thus produced, the deformed slightly elastic material withinthe key button 20 is caused to fiow into intimate contact with the irregularities provided on the coacting surface of keeper 23 by the tandem clicks or indentations 36 and 39, thus providing an effective self-locking shear engagement which will retain control key 20 in its fully seated position on the key stem 22. Preferably, clip or keeper 23.= is composed of beryllium copper or other suitable metal alloy having high elasticity and resistance to applied stresses.

It will readily be apparent to those skilled in the art that the elfectiveness of the bond thus produced between a plastic button and its associated keyboard key stem is not substantially diminished by the reduction in the structural strength of plastic materials which normally results when they are subjected to higher than normal working temperatures for considerable periods of time. There hasalso been provided an efficient locking engagement which will effectively withstand induced and internally applied forces of considerable magnitude tending to displace the control key away from its predetermined and fully seated position on the key stem.

I claim:

1. In a keyboard key assembly, the combination which comprises a relatively rigid key stem having an aperture in the-top portion thereof, a plastic control button having limited pressure flow characteristics at normal room temperatures, and a removable metallic clip-inserted between the key' stem and the plastic button, the said clip-being anchored at its upper end to said key stem and having a hook on its lower end anchored to the said key stem by engagementwith the peripheral surface of the said aperture, the said clip having laterally outwardly extending protrusions thereon plastically deforming the interior configuration of the said button in such a manner as to establish an intimate contact with the coactingsurface of the said clip and form an effective shear-resisting engagement with the said; protrusions.

2 .-:'Ihe; keyboard key assembly ofclaim 1,

wherein the metallic clip possesses high elasticity and resistance to applied stresses.

3. The keyboard key assembly of claim 2 wherein the metallic clip is composed of a beryllium copper alloy.

4. The keyboard key assembly or" claim 1 wherein the said outwardly extending rotrusions comprise a plurality of nipples plastically deforming the coacting slightly elastic material Within the said button substantially without severing material therefrom.

5. In a keyboard key assembly, the combination which comprises a relatively inelastic key stem having an aperture in the body portion thereof, a slightly elastic control button pressure-fitted onto the said key stem, and a reusable keeper operatively immovable with one extremity disposed in and engaged with a surface of said aperture and the other extremity overlying the end of the said key stem, the said keeper being interposed between the key stem and the control button and having a plurality of protuberances thereon producing an effective selflocking engagement with the said button by causing cold flow within the said button to move a portion of the said slightly elastic material into the irregularities formed by the said protuberances in the coacting surface of the said keeper.

6. The keyboard key assembly of claim 5 wherein the said keeper is composed of a highly elastic metal alloy.

7. The keyboard key assembly of claim 5 wherein the said protuberances comprise a pair of vertically aligned nipples to plastically deform the coacting interior surface of the said button substantially without the severance of material therefrom and in such a manner as to progressively establish an effective shear-resisting bond with the said buton as it is pressure fitted onto the said key stem.

JON E. GROBL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,052,616 Gardes Sept. 1, 1936 2,210,562 Anderson Aug. 6, 1940 2,304,036 Legarty Dec. 1, 1942 

